Disclosed in JP-A 56-113139, 56-104335, 62-280746, 62-280747, 62-280748, 62-280749 and 62-280750 (herein, the term "JP-A" means an unexamined and published Japanese Patent Application) is a method for preparing, in the process of color plate-making and printing, a color proof from plural black-and-white halftone dot images obtained through color separation and halftone dot image conversion was disclosed a method for preparing a color proof by the use of a silver halide color photographic material.
Recently, there has been increasingly employed a plate-making method in which images are converted to digital signals, after which image editing is carried out with a computer without the use of the above-mentioned black-and-white halftone dot images formed on photographic film. Digitization of image information enables image processing, rapidly transmitting images without regard to distance and promptly editing images by varying image lay-out as well as color tone.
As a method for outputting the thus edited images in the form of a color proof is known a method of subjecting color paper to scanning exposure with laser beams. This method, however, has various problems in practical use such as the apparatus being expensive and the functional life of light sources being short.
To enhance quality of the color proof, it is necessary to enhance monochromatic color reproducibility and firmness of black color density. In printing materials, in general, color reproduction and firm black color density can be achieved using four color inks of yellow, magenta, cyan and black. In silver halide color photographic materials, on the other hand, color images are formed in yellow, magenta and cyan dye forming layers. In this regard, however, such dilemma is faced that increasing color densities to enhance firmness of black color images result in deteriorated monochromatic reproduction and decreasing color densities to enhance the monochromatic reproduction leads to deterioration in firmness of black color images. In cases where preparing color proofs using direct positive type silver halide photographic materials, the monochromatic density may be decreased through additional minor exposure, but problems were produced such that it was difficult to control a small amount of exposure using laser light source, resulting in uneven monochromatic densities.